Every Tiny Desk Concert provides its own particular thrill, but it's not every day that we get to welcome one of NPR's 50 Great Voices to our offices. With the visit of the incredible, honey-voiced Mohammad Reza Shajarian from Iran, we lucked out by having him sing on not just any day, but on the biggest holiday of the Persian calendar: Nowruz, the New Year.

Joined by three excellent collaborators, brothers Sohrab and Tahmoures Pournazeri (celebrated musicians in their own right as leaders of Iran's Shams Ensemble) and French percussionist Robin Vassy, Ostad ("Master") Shajarian gave what amounted to a brief master class in the art of singing. In the course of this love song, titled "Az Eshgh," Shajarian unleashed torrents of swooping, soaring, goosebump-inducing sound — still perfectly controlled at age 73.

Over the past several years, Shajarian has emerged as a strong voice in other ways. Though he's been an artistic icon for decades at home, he was never particularly outspoken on political issues. But since the Green movement began in Iran in the wake of President Mahmoud Ahmadinejad's reelection in June 2009, Shajarian has openly made reference to supporting the opposition, and has demanded that state-run media stop using his songs in their broadcasts and films. Those moves carry a heavy cost: He has been effectively barred from performing live in Iran, and instead now spends most of his time touring the world to diaspora and non-Iranian audiences alike. But at his heart, Shajarian is a great artist, not a politician — and perhaps now, even more will have the chance to experience his brilliant beauty and power as a singer.